3. _Uredo rubigo_ (Red-rust, Red-rag, Red-robin) makes its appearance in the inside of the chaff-scales, and ultimately in the green epidermis of the growing grains of wheat. Its first appearance is that of oval pustules, caused by the raising of the skin, which, ultimately bursting, shows the orange-coloured spores of the epiphyte. This must not be confounded with _Cecidomyia tritici_ (wheat-midge), the larvæ of which are of a bright orange-colour; in the latter, the living moving worms may be easily detected by any common pocket lens or magnifying glass. Both these pests, to which we would apply the distinctive terms of _Uredo rubigo_ (red-rust) and _Cecidomyia tritici_ (red-gum), are exceedingly common in some seasons, and not unfrequently in the same crop. Good deep cultivation is the best remedy for the rust; but the treatment of the fly is a different matter. We would suggest the burning of smother-heaps on calm days, just as the wheat is bursting into ear, as smoke is decidedly obnoxious to these small insects, which in some seasons may be seen in thousands about the bursting wheat. 4 and 5. _Uredo linearis_; _Puccinia graminis_ (Straw-rust and Mildew).—We refer to these epiphytes under one heading, as there can be but little doubt that the latter is a more advanced state of the former. They both occur in oblong patches on the leaves and straw of wheats and other grasses: in the _uredo_ stage, of a dull red colour; in the _puccinia_ stage, of a blackish hue. They are both, as, indeed, are all these fungi, interesting microscopic objects; but our object now is to describe them popularly. Both will always be found in abundance in cold poor soils, and more especially if the finer wheats be grown in such situations. The application of a dressing of salt to the soil is said to be a preventive. Be this as it may, the disease is said to be rarer in Cheshire, where salt is so much used by the farmer, than in any other county, in as far as we have observed. Here, again, we incline to think that these are morbid affections of the plant. They are, indeed, viewed as such by Unger, in his “Die Exantheme Pflanzen,” in which the very title classes them with eruptive diseases of animals. Berkeley and Henslow, the two great authorities, however, do not accord with this view: the former remarks in reference to it—“Surely these plants are too distinctly, too regularly, and too beautifully organized to be the products of disease like warts or purulent matter in animals.” As, however, the microscope demonstrates that warts and eruptive diseases have also their special and curiously formed organisms, such a mode of reasoning is not conclusive.